This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This study aims to elucidate the heart failure-assoicated abnormalities in cardiac membrane organelles including transverse tubules (T-tubules). Studies include the EM and LM analyses of myocardium obtained from a mutant mouse model of human dilated cardiomyopathy. The unique combinatory technology developed by NCMIR to document 3D structure of T-tubes are expected to unveil its anatomical features with biological implications far greater than the hitherto recognized nature of this membrane domain, which is critical to understand the physio-pathology cardiac excitation-contraction coupling.